It might help if you fill in your profile where you are located. I don't believe the large yellow conductor should be used as a ground. At least not here in the United States.
True, NEC 250.119 only allows for Green to be used for marking conductors larger than 6 AWG as a ground.
Neutral bar, very bottom, cannot see it well, but looks like two white neutrals may be under the bottom most screw. They are quite tight together and the screw head is protruding more, indicating more wire under the screw. On neutrals, only one wire is allowed per screw. On grounds, generally, the panel instructions will allow two wires under one screw. Look at the torque chart on the inside of the door or elsewhere on the panel.
This service entrance wire is not by chance marked URD is it? URD is quite frequently found with a yellow ground. In any case, if it is URD, it is not allowed to enter the building, as it does not have a proper fire resistant insulation. URD is frequently used by power companies for services and such, but only to the meter, as this would be outside the building. URD needs to be spliced, outside the building, to something that is acceptable to enter the building.
The four square receptacle box, cannot make out for sure how many white, red and black wires either pass thru, or enter the box (not concerned with jumpers that stay inside the box) but it looks like eight, plus the two receptacles and all greens counted as one, probably exceed the fill limits for a shallow 4x4 box and that cover.
No GFCI breakers, nor receptacles. Required for grade level rooms and locations in a non-residence.
Edit: the fitting in the bottom left of the panel board is not being used correctly, It appears you have used a conduit fitting to poke thru from the inside of the panel to the 4x4 receptacle box immediately below the panel. The wires can easily chafe on the edges of the conduit fitting. They make bushings for this purpose, known as a "conduit ******" which installed with a stamped nut on the other side, allow for the tight joining of boxes. Another option would have been to use a offset ******.
Additional edit: Main panel, right side, middle of the neutral bar, between the two service cables is a green screw, which is attaching a solid copper bonding jumper from the neutral bar to the back of the panel housing, You need to REMOVE this jumper entirely from the neutral bar, and reinstall the green screw, as it is making the ground for the bonding strap that runs back across the panel to the ground bar. The small copper piece is what needs to be removed.
You do not say whether this panel is on its own meter, or if it is supplied from another panel, such as in a house. If this is supplied from a meter, and there is NO OTHER disconnect between the meter and this panel, the copper jumper should remain in place, if there is another disconnect before this panel, or if this panel is supplied from another panel, then the copper jumper should be removed from the neutral bar.
Charles
